YOKOHAMA, Japan – Top climate scientists assessing the impact of global warming say that along with the enormous risks facing humanity are opportunities to improve public health and build a better world.

Scientists from 100 countries meeting in this Japanese port city are putting finishing touches Tuesday on a massive report emphasizing the gravity of the threat facing communities from the polar regions to the tropics from climate change.

Japan's environment minister, Nobuteru Ishihara, pledged to make Tokyo's 2020 Games an "Environmental Olympics" as the city devises new policies to improve energy efficiency.

Christopher Field, co-chair of the Intergovernmental Panel on Climate Change, said the improved understanding of a warming planet will help countries grasp the human impact on that trend and how to manage those risks.